BIOMECHANICS OF PITCHING

Abstract

INTRODUCTION Baseball pitching is a complicated movement involving a series of body motions ultimately designed to propel the ball at a high velocity to a specified target. The demand for high velOCity and the repetitive nature of pitching, pitchers often throw in excess of 100 pitches over the course of a game, imposes large loads on the musculoskeletal system and increases the likelihood of injury. It has been suggested that proper pitching technique is of the utmost importance for avoiding injury (Middleton, 1990). Because of the relation between throwing mechanics and injury, there has been a strong medical interest in pitching and injury mechanisms. George Bennett, a professor of orthopedics and former semi-professional baseball player, was one of the first to academically investigate baseball injuries (Bennett, 1941). Several authors have subsequently described pathologies prevalent in pitchers. Andrews et al. (1985) discussed elbow injuries and glenoid labral tears in pitchers. Young pitchers, overly enthusiastic, increase the frequency of throwing and the forces involved, often without adequate supervision or instruction. Improper techniques may become patterns that predispose the individual to injury. Dotter (1953) first described "Little Leaguer's Shoulder" as a fracture of the humeral epiphyseal growth plate caused by baseball pitching. "Little Leaguer's Elbow" was described by Brogden and Chow (1960) to explain the association between pitching and epicondylar injuries. To more fully understand pitching mechanics, researchers have studied the overhand throwing pattern. Atwater (1979) presented an overview of throwing movements. DiGiovine et al. (1992) described the muscle activation patterns in pitching. More recently the advent of high speed video and more automated reduction of data have made the analysis of pitching more practical. Fleisig et al. (1991) described the kinematics of pitching for a sample of collegiate and professional pitchers. Felmer and Dapena (1988) reported the forces and moments acting at the shoulder and elbow for eight collegiate pitchers. Most of the previous studies that have analyzed pitching mechanics have examined collegiate, adult, or profeSSional pitchers. Little data has been presented regarding the pitching mechanics of younger athletes. The previous studies also have generally presented data on a limited number of subjects. The purpose of this paper is to review our work on pitching and to provide an overview of the kinematics and kinetics ofpitching from a large age-specific data base. In addition, the differences in pitching technique associated with age and level of experience will be discussed. The results will be presented for whole body kinematic studies of the pitching motion and for kinetic analyses of the upper extremity in pitching.